Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products.
They are produced from the hydrolysis of fats in a chemical reaction called saponification. Each soap molecule has a long hydrocarbon chain, sometimes called its ‘tail’, with a carboxylate ‘head’. In water, the
sodium or potassium ions float free, leaving a negatively-charged head.
Soap is an excellent cleanser because of its ability to act as an emulsifying agent. An emulsifier is capable of dispersing one liquid into another immiscible liquid. This means that while oil (which attracts dirt) doesn’t naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed.
The organic part of natural soap is a negatively-charged, polar molecule. Its hydrophilic (water-loving) carboxylate group (-CO2) interacts with water molecules via ion-dipole interactions and hydrogen bonding. The hydrophobic (water-fearing) part of a soap molecule, its long, nonpolar hydrocarbon chain, does not interact with water molecules. The hydrocarbon chains are attracted to each other by dispersion forces and
cluster together, forming structures called micelles. In these micelles, the carboxylate groups form a negatively-charged spherical surface, with the hydrocarbon chains inside the sphere. Because they are negatively charged, soap micelles repel each other and remain dispersed in water.
Grease and oil are nonpolar and insoluble in water. When soap and soiling oils are mixed, the nonpolar hydrocarbon portion of the micelles break up the nonpolar oil molecules. A different type of micelle then forms, with nonpolar soiling molecules in the center. Thus, grease and oil and the ‘dirt’ attached to them are caught inside the micelle and can be rinsed away.
An excavation of ancient Babylon revealed evidence that Babylonians were making soap around 2800 BC.
Babylonians were the first one to master the art of soap making. These ancient peoples used a mixture of ashes and water to remove the grease from wool and cloth, in textile production. The more this ash/water
mixture was used (and the greasier the textiles), the more soap was being formed throughout the process. This soap was the product of the alkali in the ashes reacting with the grease on the textiles.
Archaeologists have found this soap-like material in ancient clay cylinders from the time. These ancient peoples had started to cotton on to the fact that it was the combination of the ashes and the grease which was making the mixture an effective cleaning agent. The clay cylinders were inscribed with what we understand as saying, “fats boiled with ashes”; the earliest known soap recipe.
The Ebers papyrus (Egypt, 1550 BC) reveals that the ancient Egyptians mixed animal and vegetable oils with alkaline salts to produce a soap-like substance.
In the reign of Nabonidus (556–539 BC), a recipe for soap consisted of ashes, oil and sesame “for washing the stones for the servant girls”.
In ancient Palestine, the ashes from barilla plants, such as species of Salsola, saltwort and Anabasis, were used in soap production, known as potash.
The word sapo, Latin for soap, likely was borrowed from an early Germanic language and is cognate with Latin sebum, “tallow”. It first appears in Pliny the Elder’s account, Historia Naturalis, which discusses the manufacture of soap from tallow and ashes.
The Celts made their soap from animal fat and plant ashes and they named the product saipo, from which the word soap is derived.
Soapmakers in Naples were members of a guild in the late 6th century, and in the 8th century, soap-making was well known in Italy and Spain.
In Europe, soap in the 9th century was produced from animal fats and had an unpleasant smell.
Hard toilet soap with a pleasant smell was produced in the Middle East during the Islamic Golden Age, when soap-making became an established industry.
A 12th-century document describes the process of soap production. It mentions the key ingredient, alkali, which later became crucial to modern chemistry, derived from al-qaly or “ashes”.
By the 15th century, the manufacture of soap in the Christendom had become virtually industrialized, with sources in Antwerp, Castile, Marseille, Naples and Venice.
Finer soaps were later produced in Europe from the 16th century, using vegetable oils (such as olive oil) as opposed to animal fats. Many of these soaps are still produced, both industrially and by small-scale artisans.
Industrially manufactured bar soaps became available in the late 18th century, as advertising campaigns in Europe and America promoted popular awareness of the relationship between cleanliness and health.
In modern times, the use of soap has become commonplace in industrialized nations due to a better understanding of the role of hygiene in reducing the population size of pathogenic microorganisms.
Until the Industrial Revolution, soapmaking was conducted on a small scale and the product was rough.
During the Restoration era a soap tax was introduced in England, which meant that until the mid-1800s, soap was a luxury, used regularly only by the well-to-do.
William Gossage produced low-priced, good-quality soap from the 1850s.
American manufacturer Benjamin T. Babbitt introduced marketing innovations that included the sale of bar soap and distribution of product samples.
William Hesketh Lever and his brother, James, bought a small soap works in Warrington in 1886 and founded what is still one of the largest soap businesses, formerly called Lever Brothers and now called Unilever.
Liquid soap was not invented until the nineteenth century in 1865, William Shepphard patented a liquid version of soap.
In 1898, B.J. Johnson developed a soap derived from palm and olive oils – his company, the B.J. Johnson Soap Company, introduced “Palmolive” brand soap that same year. This new brand of soap became popular rapidly, and to such a degree that B.J. Johnson Soap Company changed its name to Palmolive.
A soap bubble is an extremely thin film of soapy water enclosing air that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. They are often used for children’s enjoyment, but they are also used in artistic performances. Assembling several bubbles results in foam.
The largest soap sculpture measures 2.19 x 2.07 x 2.68 m (7.19 x 6.79 x 8.80 ft) and was created by Protex Soap (South Africa) in Johannesburg, South Africa, on 5 October 2010. The sculpture represents a globe held by two hands.
The largest bar of soap weighs 14.45 tonnes and was achieved by Jinan Rujia Co., Ltd. (China) in Jinan, Shandong, China on 11 December 2015. The soap took over 3 months to complete and was divided up in to smaller pieces after the attempt to be sold.